Brendan Steele fired a final-round 69 on Sunday to win the US PGA Tour Safeway Open for the second straight year.
Steele, who started the day two shots off the lead of rookie Tyler Duncan, finished with a 15-under total of 273 for a two-shot triumph over Tony Finau.
Finau also closed with a 69 at Silverado Resort and Spa in Napa, California.
Five-time major winner Phil Mickelson, seeking his first win since the 2013 British Open, was within one stroke of the lead late in the round but settled for a share of third place after a 70 for 276. He was tied with fellow American Chesson Hadley, who sined for a 73.
Duncan, who had led or shared the lead after each of the first three rounds, got off to a disastrous start with three bogeys to open his round.
He carded a 75 to share fifth with Canadian Graham DeLaet (72) on 277.
Steele, meanwhile, forged ahead with three birdies on the front nine.
One of his two bogeys came at the 14th, where he was in two bunkers and delighted to drop only one shot thanks to a seven-foot bogey putt.
"That was huge," said Steele, adding that after "making a complete mess" of the hole "that putt felt as good as any."
Steele said the winds made the final round more challenging, not only because of their strength but because they were from a different direction than they had been all week.
"This was a brutal wind today," he said. "Lots of holes into the wind, lots of uncomfortable shots."
Mickelson pulled within one shot of Steele's lead with a birdie at the 16th.
But he followed that with a bogey at 17 before a closing birdie at the par-five 18th.
"I had a good time today," Mickelson said. "It was fun to be in the mix, it was fun to have a chance.
"It was very difficult conditions. I enjoy that challenge. This course played totally different with the firm greens and the wind and some of the high pin placements were tough to get to."
But the 47-year-old American remains encouraged by the state of his game, and his prospects for winning again soon.
"It's just easy to see the ball start on the right line," he said. "Iron play is back, distance, control, putting, the game has just come back."
The tournament kicked off the US PGA Tour's 2017-18 season, and Steele said that he hoped the victory would again prove a springboard to a successful campaign.
"It really was a good springboard for me last year," he said. "It propelled me to my best season yet."
Steele said he faltered late in the season as he felt the pressure to make the Tour championship.
"It was nice to get re-started here and feel a little bit more free," he said.